High molecular, thermoplastically processable polycarbonate elastomers based on "soft segments" and diphenols and their preparation are known (see, for example, U.S. Pat. No. 3,161,615; U.S. Pat. No. 3,030,335; U.S. Pat. No. 3,287,442; U.S. Pat. No. 3,189,662; German Auslegeschrift No. 1,162,559; German Offenlegungschrift No. 2,636,783; German Offenlegungschrift No. 2,702,626; German Offenlegungschrift No. 2,619,831; German Offenlegungschrift No. 2,636,784; German Offenlegungschrift No. 2,650,533; German Offenlegungschrift No. 2,726,416; German Offenlegungschrift No. 2,651,639; German Offenlegungschrift No. 2,726,376; German Offenlegungschrift No. 2,712,435; German Offenlegungschrift No. 2,726,417; German Patent Application No. P 28 27 325.8 and German Patent Application P 28 37 526.0).
The products are thermoplastically processable and have a high degree of elasticity. The elasticity of these products depends on the relative proportions of hard and soft segments; the elasticity and elongation at break increasing with an increasing proportion of soft segments. These products also have a relatively high heat distortion temperature due to regions of crystalline aromatic polycarbonate which impart to the polymer a high density of physical cross-linking. The disadvantage of almost all these products is that the aromatic polycarbonate segments which give the polymer its high heat distortion temperature by physical cross-linking do not recrystallize rapidly enough after thermoplastic processing, resulting in that the polycarbonate elastomer products tend to stick to each other.
This tackiness could hitherto be eliminated only by expensive processing methods such as, for example, by heat treatment or by drawing and heat treatment (see German Offenlegungsschrift No. 2,636,784 and German Offenlegungsschrift No. B 2,636,783, after the thermoplastic processing. The production of nontacky products thus have been associated with a considerable expenditure of work.
The irradiation of aromatic polycarbonates containing aromatic keto groups is described in German Patent Application Nos. P 27 46 141.2 and P 28 29 256.0. (For the irradiation of aromatic polycarbonates, see also German Offenlegungschriften Nos. 2,746,139 and 2,746,140 and German Patent Application Nos. P 28 29 258.2; P 28 29 257.1; P 28 29 259.3 and P 28 42 004.4. However, in contrast to the cross-linkable polycarbonate elastomers according to the present invention, these cross-linkable aromatic polycarbonates contain no soft segments and no "tackiness" is associated with their processing. It could, therefore, not be predicted that by irradiating the polycarbonate elastomers according to the invention, the tackiness disappears without causing the elastomers to embrittle and/or to lose their transparency.
The polycarbonate elastomers according to the invention can be irradiated after processing and the tackiness of moldings, films, etc. of the cross-linkable polycarbonate elastomers can thus be eliminated in a simple manner.
In the field of packaging of medicines, films are used which must be sterilized by steam at 121.degree. C. without exhibiting distortion. The cross-linking according to the invention of the polycarbonate elastomers obtainable according to the invention produces films which fulfill these requirements and, compared with films of corresponding noncross-linked polycarbonate elastomers, have a significantly higher heat distortion temperature.
The packaging materials hitherto used for biological liquids and parenteral agents consisted of polyvinyl chloride containing a high proportion of plasticizer. Such packaging materials have certain disadvantages caused by the high plasticizer content and by the impurities present in PVC; on prolonged use, this is particularly troublesome from a medical point of view.
In contrast, the use according to the invention of the segmented cross-linked polycarbonate elastomers as packaging materials is free of the above-mentioned disadvantages, and feature high mechanical strength, extremely low contents of processing auxiliaries, outstanding transparency and physiological inertness.
In the field of packaging of medicines, glass containers, in particular bottles, have been replaced to an increasing extent by bottles made of thermoplastics, in particular polypropylene, polyethylene and polyethylene terephthalate. All these "rigid" containers have the fundamental disadvantage that upon removal of their contents, they must be aerated under sterile conditions so that the vacuum unavoidably formed can be removed without evaporation of the biological liquids and parenteral agents.
By contrast, aeration is not necessary when emptying containers made of packaging materials obtained from the segmented cross-linked polycarbonate elastomers of the present invention.
The packaging materials obtained from the segmented cross-linked polycarbonate elastomers are outstandingly suitable for packaging and storing biological liquids such as blood, blood plasma or protein fractions as well as for storing infusion liquids or other parenteral agents.